Technical Field
[0001] The present invention relates to a briquette for use as steelmaking material and
a method for forming the same and more particularly to a technique for effectively
utilizing grinding chips from an iron-based metal.
BACKGROUND ARTS
[0002] Grinding chips which occur in the machining of an iron-based metal such as bearing
steel, carburized steel and the like (hereinafter, the term "machining" will be used
to represent a concept also including grinding, super-finishing grinding, lapping
and the like) are recovered in the form of cotton-like (fibrous) aggregates including
a grinding fluid containing water and oil, abrasive grains, and the like. Since the
cotton-like aggregates contain a considerable quantity of pure iron, there have been
made attempts to reuse the aggregates as steelmaking material. Unfortunately, however,
the cotton-like aggregates contain such a large quantity of water that bumping (phreatic
explosion) will be caused by the water if the aggregates are directly charged into
a blast furnace. It may be contemplated to remove the water from the cotton-like aggregates
by centrifugation or the like. In this case, however, the oil contained in the cotton-like
aggregates is also removed along with the water and hence, the pure iron as a component
of the grinding chips is converted to iron oxide due to the self heating of the cotton-like
aggregates. Therefore, the resultant aggregates need be reduced so as to be reused
as steelmaking material. The use of a reducing agent results in increased costs.
[0003] On the other hand, the grinding chips with the oil adhered thereto are prone to adhered
to each other. Hence, the compression molding of the cotton-like aggregates involves
difficulty about accomplishing solidification to a desired strength. Furthermore,
in the case of cotton-like aggregates containing a large quantity of grinding chips
from an iron-based metal containing not less than 0.2 wt% of carbon, the aggregates
present such a great springback when compressed that it is difficult to accomplish
the solidification to a desired strength by compression molding the aggregates. Accordingly,
if such compacted cotton-like aggregates are charged into the blast furnace, the aggregates
are scatteringly carried upward so that most of them is collected by a dust collector.
[0004] In addition, the fibrous grinding chips contained in the cotton-like aggregates are
hard to crush by means of a hammer mill or the like and hence, the cotton-like aggregates
cannot be sheared finely. This leads to a difficulty of processing the cotton-like
aggregates into briquettes or the like.
[0005] In reality, therefore, the cotton-like aggregates are not put to reuse but committed
to a waste processing contractor for landfill disposal.
[0006] In a steel making process including a smelting step and the like, there occur dusts
bearing iron and heavy metals. Hence, it is a general practice to collect such dusts
as recovery dusts (OG dusts) (see, for example, Unexamined Japanese Patent Publication
No.7(1995)-97638). Unfortunately, if such recovery dusts are directly charged into
the blast furnace, the dusts are scatteringly carried upward to be collected by the
dust collector again. As a result, the dusts are not put to reuse but committed to
the landfill disposal.
[0007] However, the landfill disposal is not desirable from the standpoint of the effective
utilization of resources. Furthermore, the landfill disposal entails the environmental
deterioration as well as the increase of the disposal cost. The recovery dusts, in
particular, requires an even greater disposal cost because the dusts contain heavy
metals and must be committed to the landfill disposal as special industrial wastes.
[0008] It is an object of the invention to provide a briquette for use as steelmaking material
permitting an effective reuse of grinding chips, as well as a method for forming the
same.
[0009] It is another object of the invention to provide a briquette for use as steelmaking
material permitting an effective reuse of recovery dusts along with the grinding chips,
as well as a method for forming the same.
DISCLOSURE OF THE INVENTION
[0010] A briquette for use as steelmaking material according to the invention, which contains
powdery pure iron and oil and which is dried, the briquette is formed by solidifying
powder using a solidification assistant, the powder obtained by finely shearing cotton-like
aggregates containing grinding chips from an iron-based metal (Claim 1).
[0011] The so-formed briquette for use as steelmaking material is a dry solid mass and hence,
the briquette is unlikely to cause bumping or to be scatteringly carried upward if
it is directly charged into a blast furnace. In addition, the handlings, such as transportation,
storage and the like, of the briquette are easy. Since the briquette contains oil,
the oxidization of the powdery pure iron is suppressed. Therefore, the briquette can
be reused as a high-quality steelmaking material, thus contributing to the environmental
conservation as well as to the reduction of disposal cost of the grinding chips.
[0012] The above briquette for use as steelmaking material may further contain coke powder
(Claim 2). In this case, because of the solidification assistant and coke, the quite
rigidly solidified briquette can be formed simply by compression molding the powder.
[0013] The briquette for use as steelmaking material containing coke may further contain
recovery dusts collected in a steelmaking process (Claim 3). In this case, the recovery
dusts can be reused together with the grinding chips after solidification.
[0014] It is preferred that the solidification assistant is at least one selected from the
group consisting of ricepolishings,blackstrap molasses,starches,calcined lime, coloidal
silica, silicate of soda, aluminum phosphate, vinyl acetate sludge, asphalt emulsion
and bentonite (Claim 4). The assistant provides the rigid solidification despite the
presence of the oil. Hence, the handlings, such as transportation, storage and the
like, of the briquette are further facilitated.
[0015] A briquette for use as steelmaking material according to the invention, which contains
powdery pure iron and oil and which is dried, the briquette is formed by impregnating
a brittle compact with an inorganic solidification assistant for solidification, the
brittle compact formed by compression molding cotton-like aggregates containing grinding
chips from an iron-based metal (Claim 5).
[0016] This briquette is a dried solid mass, as well. Hence, the briquette is unlikely to
cause bumping or to be sactteringly carried upward if it is directly charged into
the blast furnace. In addition, the handlings, such as transportation, storage and
the like, of the briquette are easy. Since the briquette contains oil, the oxidization
of the powdery pure iron is suppressed. Therefore, the briquette can be reused as
a high-quality steelmaking material, thus contributing to the environmental conservation
as well as to the reduction of disposal cost of the grinding chips. In this briquette
for use as steelmaking material, it is preferred that the inorganic solidification
assistant is at least one selected from the group consisting of coloidal silica, silicate
of soda and aluminum phosphate (Claim 6). The material provides the rigid solidification
despite the presence of the oil. Hence, the handlings, such as transportation, storage
and the like, of the briquette are further facilitated.
[0017] It is preferred that each of the above briquettes for use as steelmaking material
contains 2 to 30 wt% of solidification assistant(Claim 7), so that the briquette is
solidified even more rigidly. Thus, the handlings, such as transportation, storage
and the like, of the briquette are further facilitated.
[0018] It is preferred that each of the above briquettes is substantially shaped like a
pillow (Claim 8). In this case, the briquette can be increased in compressive strength
and is less likely to incur partial fracture. Hence, the handlings, such as transportation,
storage and the like, of the briquette are further facilitated.
[0019] A method for forming a briquette for use as steelmaking material according to the
invention comprises in this order: a step of compression molding cotton-like aggregates
containing grinding chips from an iron-based metal and a grinding fluid containing
oil and water, thereby forming a brittle compact in which the fibrous grinding chips
are roughly sheared and which is removed of excessive water and oil; a step of crushing
the brittle compact for further finely shearing the grinding chips, and mixing the
resultant grinding chips with a solidification assistant for obtaining powder containing
the solidification assistant; a step of forming a briquette by compression molding
a predetermined amount of the powder for solidification; and step of drying the resultant
briquette (Claim 9).
[0020] According to the so-arranged method for forming the briquette for use as steelmaking
material, the rough shearing of the fibrous grinding chips, which is hard to accomplish
by the prior art, can be done easily by compression molding the cotton-like aggregates.
In the step of crushing the brittle compact, the rough shearing of the fibrous grinding
chips in the brittle compact have been done previously so that the grinding chips
can be sheared in an easy and effective manner. Thus, the fine powdery particles can
be obtained in an easy and positive manner. Furthermore, because of the solidification
assistant present in the powder, the solidification to a desired strength can be achieved
simply by compression molding the powder. In addition, the aforementioned steps are
performed as retaining the oil contained in the grinding fluid and hence, the oxidization
of the pure iron as a component of the grinding chips can be suppressed. Therefore,
the cotton-like aggregates can be reused as a high-quality steelmaking material, thus
contributing to the environmental conservation as well as to the reduction of disposal
cost of the grinding chips.
[0021] It is preferred that at least one selected from the group consisting of rice polishings,
blackstrap molasses, starches, calcined lime, coloidal silica, silicate of soda, aluminum
phosphate, vinyl acetate sludge, asphalt emulsion and bentonite is employed as the
solidification assistant by the above method for forming the briquette for use as
steelmaking material (Claim 10). The assistant provides the easy and rigid solidification
of the powder containing oil. Thus is obtained the briquette for use as steelmaking
material which features easy handlings such as transportation, storage and the like.
[0022] In the above method for forming the briquette for use as steelmaking material, it
is preferred that the solidification assistant is admixed in an amount of 2 to 30
wt% (Claim 11). This provides an even more rigid solidification of the powder. Thus
is obtained the briquette for use as steelmaking material featuring even easier handlings
such as transportation, storage and the like.
[0023] Another method for forming a briquette for use as steelmaking material according
to the invention comprises in this order: a step of compression molding cotton-like
aggregates containing grinding chips from an iron-based metal and a grinding fluid
containing oil and water, thereby forming a brittle compact in which the fibrous grinding
chips are roughly sheared and which is removed of excessive water and oil; a step
of impregnating the brittle compact with a solidification assistant; and a step of
drying the brittle compact impregnated with the solidification assistant(Claim 12).
[0024] According to the so-arranged method for forming the briquette for use as steelmaking
material, the rough shearing of the fibrous grinding chips, which is hard to accomplish
by the prior art, can be done easily by compression molding the cotton-like aggregates.
Furthermore, because of the solidification assistant impregnated into the brittle
compact, the solidification to a desired strength can be achieved simply by compression
molding the brittle compact. In addition, the aforementioned steps are performed as
retaining the oil contained in the grinding fluid and hence, the oxidization of the
pure iron as a component of the grinding chips can be suppressed. Therefore, the cotton-like
aggregates containing grinding chips can be reused as a high-quality steelmaking material,
thus contributing to the environmental conservation as well as to the reduction of
disposal cost of the grinding chips. Furthermore, the briquette can be formed efficiently
because the solidification can be accomplished without finely crushing the cotton-like
aggregates.
[0025] It is preferred that at least one selected from the group consisting of coloidal
silica, silicate of soda and aluminum phosphate is employed as the solidification
assistant by the above method for forming the briquette for use as steelmaking material
(Claim 13). The assistant provides the easy and rigid solidification of the brittle
compact containing oil. Thus is obtained the steelmaking material featuring easy handlings
such as transportation, storage and the like. In this method, it is preferred that
the solidification assistant is impregnated in an amount of 2 to 30 wt% (Claim 14).
This provides an even more rigid solidification of the brittle compact and hence,
there may be obtained the briquette for use as steelmaking material featuring even
easier handlings such as transportation, storage and the like.
[0026] Still another method for forming a briquette for use as steelmaking material according
to the invention comprises in this order: a step of compression molding cotton-like
aggregates containing grinding chips from an iron-based metal and a grinding fluid
containing oil and water, thereby forming a brittle compact in which the fibrous grinding
chips are roughly sheared and which is removed of excessive water and oil; a step
of crushing the brittle compact for further finely shearing the grinding chips, and
mixing the resultant grinding chips with coke and a solidification assistant for obtaining
powder containing the coke and solidification assistant; a step of forming a briquette
by compression molding a predetermined amount of the powder for solidification; and
a step of drying the resultant briquette (Claim 15).
[0027] In the so-arranged method for forming the briquette for use as steelmaking material,
as well, the rough shearing of the fibrous grinding chips, which is hard to accomplish
by the prior art, can be readily done by compression molding the cotton-like aggregates.
In the step of crushing the brittle compact, the rough shearing of the fibrous grinding
chips in the brittle compact have been done previously so that the grinding chips
can be sheared in an easy and effective manner. Thus, the fine powdery particles can
be obtained in an easy and positive manner. Furthermore, because of the effect of
the coke and the like present in the powder, the quite rigidly solidified briquette
for use as steelmaking material can be obtained simply by compression molding the
powder. In addition, the above steps are performed as retaining the oil contained
in the grinding fluid and hence, the oxidization of the pure iron as a component of
the grinding chips can be suppressed. Therefore, the cotton-like aggregates can be
reused as a high-quality steelmaking material, thus contributing to the environmental
conservation as well as to the reduction of disposal cost of the grinding chips. Furthermore,
there may be obtained the briquette for use as steelmaking material containing the
coke serving as a carburization material and a reducing agent, thus featuring a higher
added value.
[0028] In the above method for forming the briquette for use as steelmaking material, the
crushed brittle compact may be further admixed with recovery dusts collected in a
steelmaking process (Claim 16). This permits the recovery dusts to be reused together
with the grinding chips after solidification, thus contributing to the environmental
conservation as well as to the reduction of the disposal cost of the recovery dusts.
[0029] In this method for forming the briquette for use as steelmaking material, it is preferred
that the recovery dusts are admixed in an amount of 10 to 30 wt% (Claim 17). This
permits a briquette of a desired hardness to be formed easily. It is preferred that
at least one selected from the group consisting of rice polishings, blackstrap molasses,
starches, calcined lime, coloidal silica, silicate of soda, aluminum phosphate, vinyl
acetate sludge, asphalt emulsion and bentonite is employed as the solidification assistant
(Claim 18). The assistant provides an easy and stable solidification of the powder
containing oil. It is further preferred that the solidification assistant is admixed
in an amount of 1 to 10 wt% (Claim 19). This provides an even easier and more stable
solidification of the powder. On the other hand, it is further preferred that the
coke is admixed in an amount of 5 to 50 wt% (Claim 20). This permits the briquette
for use as steelmaking material to be solidified even more rigidly.
[0030] In all of the aforementioned methods for forming the briquette for use as steelmaking
material, it is preferred that the employed cotton-like aggregates are adjusted for
the content of water to less than 50 wt% and for the content of oil to less than 10
wt% (Claim 21). This results in easy handlings, such as transportation and the like,
of the cotton-like aggregates and also permits excessive water and oil to be readily
and adequately removed from the brittle compact only by the compression molding.
[0031] In all of the aforementioned methods for forming the briquette for use as steelmaking
material, it is preferred that the brittle compact is adjusted for the content of
water to 2 to 12 wt% and for the content of oil to 1 to 5 wt% (Claim 22). In this
case, the brittle compact can be solidified to a suitable hardness while the oxidization
of the grinding chips can be effectively suppressed by the minimum amount of residual
oil.
[0032] In all of the aforementioned methods for forming the briquette for use as steelmaking
material, it is preferred that immediately after the compression molding, the briquette
is subjected to quick cooling (Claim 23). This permits the briquette to be solidified
in an easy and stable manner.
[0033] In all of the aforementioned methods for forming the briquette for use as steelmaking
material, it is preferred that a product substantially shaped like a pillow is obtained
as the briquette (Claim 24). In this case, there may be obtained a briquette which
has a high compressive strength and is less likely to incur partial fracture and which
features even more easier handlings such as transportation, storage and the like.
[0034] In all of the aforementioned methods for forming the briquette for use as steelmaking
material, a material containing not less than 0.2 wt% of carbon may be employed as
the grinding chips (Claim 25). In the case of cotton-like aggregates containing the
grinding chips having such a great springback, as well, the cotton-like aggregates
can be rigidly solidified while eliminating the influence of the springback.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035]
Fig.1 is a partially cut-away perspective view showing a briquette for use as steelmaking
material according to one embodiment of the invention.
Fig.2 is a group of diagrams showing steps of a method for forming the briquette for
use as steelmaking material according to one embodiment of the invention.
Fig.3 is a group of diagrams showing steps of a method for forming the briquette for
use as steelmaking material according to another embodiment of the invention.
Fig. 4 is a group of diagrams showing steps of a method for forming the briquette
for use as steelmaking material according to still another embodiment of the invention.
BEST MODES FOR CARRYING OUT THE INVENTION
[0036] Fig.1 is a partially cut-away perspective view showing a briquette for use as steelmaking
material according to one embodiment of the invention. The briquette A contains powdery
pure iron and oil, and is formed by solidifying powder using a solidification assistant,
the powder obtained by finely shearing cotton-like aggregates containing grinding
chips from an iron-based metal and a grinding fluid containing oil and water; and
drying the solidified product for removal of the water. The briquette
A is substantially shaped like a pillow.
[0037] Fig. 2 is a group of diagrams showing steps of a method for forming the briquette
A. In the forming of the briquette
A, cotton-like aggregates
B (see Fig.2(a)) of grinding chips produced by machining an iron-based metal are first
compressed for preparatory adjustment of contents of water and oil which are components
of the grinding fluid contained in the cotton-like aggregates
B. The cotton-like aggregates
B are compressed by, for example, being clamped between a pair of rollers 2 as being
carried on a belt conveyor 1 (see Fig.2(b)). It is preferred in this process that
the cotton-like aggregates are adjusted for the content of water to less than 50 wt%
and for the content of oil to less than 10 wt%. This facilitates the handlings, such
as transportation, storage and the like, of the cotton-like aggregates
B.
[0038] Next, the cotton-like aggregates
B thus adjusted for the contents of water and oil are compression molded in a mold
3 using a press thereby forming a brittle compact
C (see Fig.2(c)). The grinding chips shaped like spiral fiber contained in the cotton-like
aggregates
B are roughly sheared by the compression molding. Additionally, excessive water and
oil are removed such that the brittle compact
C is adjusted for the content of water to 2 to 12 wt% and for that of oil to 1 to 5
wt%. Thus, the oxidization of the grinding chips is effectively suppressed by the
minimum possible amount of residual oil. Furthermore, the cotton-like aggregates B
have been adjusted for the content of water to less than 50 wt% and for the content
of oil to less than 10 wt% in the pervious step and hence, the contents of water and
oil in the brittle compact
C can be easily and properly adjusted only by the compression molding.
[0039] The brittle compact
C is formed in a shape easy to handle, such as circular cylinder, sphere, prism or
the like, and is compacted to such a strength as not to collapse when sent to the
subsequent step.
[0040] Next, the brittle compact
C together with a solidification assistant
D are charged in a mixer 5 equipped with a chopper having rotary blades 4 (or a Henschel
mixer) for crushing (see Fig.2(d)). Thus, the grinding chips in the brittle compact
C are further finely sheared (finishing shearing) and thus is obtained powder
E containing powdery pure iron and the solidification assistant
D (see Fig.2(e)). The powdery pure iron has a greater diameter of the order of 3 to
1000 µm. In the crushing of the brittle compact
C, the finishing shearing can be smoothly done because the fibrous grinding chips in
the brittle compact
C have previously been subjected to the rough shearing. In a case where the fibrous
grinding chips in the brittle compact
C are not roughly sheared, it is extremely difficult to crush the compact
C by means of the mixer 5. Accordingly, it is impossible to obtain the fine powder
E.
[0041] As the solidification assistant
D, there may preferably be employed one or more than one selected from the group consisting
of rice polishings (refined rice polishings), blackstrap molasses such as from sugar
cane, starches such as potato starch, corn starch and the like, calcined lime, coloidal
silica, silicate of soda, aluminum phosphate, vinyl acetate sludge, asphalt emulsion,
and bentonite. The solidification assistant
D may preferably be present in concentrations of 2 to 30 wt%. The rice polishings and
blackstrap molasses are particularly preferred as the solidification assistant
D because they are effective to prevent the powdery pure iron from being altered in
quality and are less costly. After kneading, the asphalt emulsion is separated into
an asphalt component and water, the asphalt component presenting caking which develops
strength. Anionic asphalt is preferably used in the asphalt emulsion.
[0042] Subsequently, a predetermined amount of the above powder
E is compression molded in a mold 6 using a press (see Fig.2(f)), thereby forming a
water-containing briquette
F which contains a large quantity of pure iron and is substantially shaped like a pillow.
In the compression molding of the powder
E, the pure iron particles with oil adhered thereto are firmly bonded together via
the water contained in the solidification assistant
D and powder
E whereby the powder
E can be solidified. Particularly, in a case where the powder
E contains 5 to 6 wt% of water, 4 wt% of rice polishings and 2 wt% of blackstrap molasses
or where the powder
E contains 7 to 15 wt% of water and 2 to 10 wt% of vinyl acetate sludge, there may
be obtained a water-containing briquette
F more rigidly solidified.
[0043] The phrase "substantially shaped like a pillow" means a shape having a rounded circumferential
edge and gradually increased in thickness from the circumferential edge toward its
center, the shape including those of eggs, almond, rugby ball and the like. Forming
the powder into such a shape gives the briquette
A which is hard to collapse withstanding the compressive load and is less likely to
incur partial fracture at a corner portion thereof or the like.
[0044] Immediately after the compression molding, the water-containing briquette
F is subjected to quick cooling by applying thereto air blow at normal temperatures
or cooled air blow (see Fig.2(g)). This provides an easy and stable solidification
of the water-containing briquette
F. Subsequently, the water-containing briquette
F is cured (dried) for removal of the water contained therein (see Fig.2(h)). Thus
is obtained the briquette
A for use as steelmaking material (see Fig.2(i)). It is preferred to perform the curing
of the briquette for about two days in the light of the assured removal of the contained
water.
[0045] The briquette
A thus formed has a porous nature resulting from the solidification of the powder
E and hence, the water contained therein can be easily and assuredly removed by curing.
Accordingly, if the briquette is directly charged into the blast furnace, there is
no fear of causing bumping or of being scatteringly carried upward to be discharged.
In addition, the oxidization of the pure iron is effectively suppressed because the
processing is performed as retaining a part of the oil of the grinding fluid at all
times. As to a briquette
A formed from cotton-like aggregates B containing grinding chips from a bearing steel
(SUJ-2), for example, it is confirmed that the pure iron is present in concentrations
of 84 to 95 wt%. Accordingly, the briquette
A presents at least 90% of a high smelting yield to be worthy of a high-quality steelmaking
material which can be offered to steel makers for pay. Furthermore, the briquette
is in the solid form, thus facilitating the transportation and other handlings thereof.
[0046] Fig. 3 is a group of diagrams showing steps of another method for forming the briquette
A of the invention. This method differs from the method of Fig. 2 in that the step
of crushing the brittle compact
C is dispensed with. That is, the method forms the brittle compact
C from the cotton-like aggregates
B just the same way as in the method shown in Fig.2 (see Figs.3(a)-(c)). The contents
of water and oil of this brittle compact
C are the same as those of the compact obtained by the method shown in Fig.2.
[0047] Then, the brittle compact
C obtained through these steps is impregnated with a solidification assistant
D in liquid form. The impregnation with the solidification assistant
D is performed by, for example, immersing the brittle compact C in the solidification
assistant
D filled in a tank 8 as carrying the compact on a belt conveyor 7 (see Fig.3(d)). As
the solidification assistant
D, there may preferably be employed at least one selected from the group consisting
of coloidal silica, silicate of soda, and aluminum phosphate. The solidification assistant
D may preferably be impregnated in concentrations of 2 to 30 wt%. This permits the
brittle compact
C to be readily and rigidly solidified.
[0048] Subsequently, the brittle compact
C impregnated with the solidification assistant
D (see Fig.3(e)) is cured (dried) (see Fig.3(f)), and thus is obtained the briquette
A for use as steelmaking material (see Fig.3(g)). For curing, the compact may be quickly
cooled by applying thereto air blow at normal temperatures or cooled air blow.
[0049] The briquette
A thus formed can present the same effect as the briquette
A formed by the method shown in Fig.1. In addition, the method shown in Fig.3 is more
efficient in forming the briquette
A because it omits the step of crushing the brittle compact
C.
[0050] Besides the circular cylinder shape shown in the figure, the briquette
A may also take a substantially pillow-like shape, such as of eggs, almond, rugby ball
and the like. The pillow-like shape has a rounded circumferential edge and is gradually
increased in thickness from the circumferential edge toward its center.
[0051] The methods for forming the briquette shown in Figs. 2 and 3 are preferably applied
to the reuse of grinding chips containing not less than 0.2 wt% of carbon. Such grinding
chips present a great springback and hence, are hard to solidify. However, the application
of the inventive method permits the rigidly solidified briquette
A to be formed easily, eliminating the influence of the springback of the grinding
chips. A typical example of the grinding chips containing not less than 0.2 wt% of
carbon includes grinding chips from a bearing steel.
[0052] In the foregoing embodiment, the crushing of the brittle compact
C is performed concurrently with the admixing of the solidification assistant
D. However, the crushing of the brittle compact
C and the admixing of the solidification assistant
D may be performed in separate steps.
[0053] The briquette
A of the invention may further contain coke powder. Alternatively, the inventive briquette
A may further contain the coke powder and recovery dust powder collected in the steelmaking
process.
[0054] Fig. 4 is a group of diagrams showing steps of a method for forming a briquette
A further containing the coke powder and the recovery dust powder. In this method of
forming the briquette
A, a brittle compact
C is formed from the cotton-like aggregates
B just the same way as in the method shown in Fig.2 (see Figs.4(a)-(c)). The contents
of water and oil of the brittle compact
C are also the same as those of the compact obtained by the method shown in Fig.2.
[0055] Next, the brittle compact
C together with coke
K, recovery dusts
S produced and collected in the steelmaking process, and the solidification assistant
D are charged into a mixer 5 equipped with a chopper having rotary blades 4 (or a Henschel
mixer) for crushing (see Fig.4(d)). In this step, 50 to 70 wt% of the brittle compact
C, 5 to 50 wt% of the coke
K, 10 to 30 wt% of the recovery dusts
S and 1 to 10 wt% of the solidification assistant
D are blended together.
[0056] Thus, the grinding chips in the brittle compact
C are further finely sheared (finishing shearing), and thus is obtained powder
E containing the pure iron, coke
K, recovery dusts
S and powdery solidification assistant
D (see Fig.4(e)).
[0057] Similarly to the embodiment shown in Fig.2, one or more than one selected from the
group consisting of rice polishings, blackstrap molasses such as from sugar cane,
starches, calcined lime, coloidal silica, silicate of soda, aluminum phosphate, vinyl
acetate sludge, asphalt emulsion and bentonite are preferably employed as the solidification
assistant
D. As the recovery dusts
S, for example, there may be employed those containing 10 to 55 wt% of iron (total Fe)
which are produced and collected in the steelmaking process.
[0058] The subsequent steps are the same as those shown in Fig.2. Specifically, a predetermined
amount of the above powder
E is compression molded by means of, for instance, a roller type molding machine or
a cylinder type molding machine 6 (see Fig.4(f)), thereby forming a briquette
F substantially shaped like a pillow and containing a large quantity of pure iron.
In the compression molding of the powder
E, the pure iron particles with oil adhered thereto are firmly bonded together via
the water contained in the coke
K, solidification assistant
D and the powder
E whereby the powder E can be solidified. Immediately after the compression molding,
the briquette
F is subjected to quick cooling by applying thereto air blow at normal temperatures
or cooled air blow (see Fig.4(g)). Then, the briquette
F is cured (dried) for removal of the water contained therein (see Fig.4(h)) and thus
is obtained the briquette
A for use as steelmaking material (see Fig.4(i)).
[0059] The resultant briquette
A is also formed by solidifying the powder
E and hence, can be readily and assuredly removed of the water contained therein by
curing. Accordingly, if the briquette is directly charged into the blast furnace,
there is no fear of causing bumping or of being scatteringly carried upward to be
discharged. In addition, the oxidization of the pure iron is effectively suppressed
because the processing is performed as retaining a part of the oil of the grinding
fluid at all times. Furthermore, the briquette features a higher added value because
it further contains the coke
K serving as a carburizationmaterial and a reducing agent. What is more, the briquette
is in the solid form, thus facilitating the transportation and other handlings thereof.
[0060] The above forming method, in particular, provides a more rigidly solidified briquette
A for use as steelmaking material because 5 to 50 wt% of coke and 1 to 10 wt% of solidification
assistant are admixed. In addition, the method permits the briquette of a desired
hardness to be formed easily because the mixing ratio of the recovery dusts is defined
to range from 10 to 30 wt%.
[0061] The above method for forming the briquette A is also particularly preferably applied
to the reuse of the grinding chips containing not less than 0.2 wt% of carbon.
[0062] In the above embodiment, the crushing of the brittle compact
C is performed concurrently with the admixing of the coke
K, recovery dusts
S and solidification assistant
D. However, the crushing of the brittle compact
C and the admixing of the coke
K and the like may be performed in separate steps. The above embodiment may be practiced
without admixing the recovery dusts
S.
1. A method for forming a briquette for use as steelmaking material,
comprising the following steps in this order:
- a step of compression molding cotton-like aggregates (B) containing grinding chips
from an iron-based metal and a grinding fluid containing oil and water, thereby forming
a brittle compact (C) in which the fibrous grinding chips are roughly sheared and
from which excessive water and oil is removed;
- a step of crushing the brittle compact (C) for further finely shearing the grinding
chips, and mixing the resultant grinding chips with a solidification assistant (D)
for obtaining powder (E) containing the solidification assistant (D);
- a step of forming a briquette by compression molding a predetermined amount of the
powder (E) for solidification; and
- a step of drying the resultant briquette (A).
2. The method according to claim 1,
wherein at least one selected from the group consisting of rice polishings, blackstrap
molasses, starches, calcined lime, colloidal silica, silicate of soda, aluminum phosphate,
vinyl acetate sludge, asphalt emulsion and bentonite is employed as the solidification
assistant (D).
3. The method according to claim 1 or 2,
wherein the solidification assistant (D) is admixed in an amount of 2 to 30 wt%.
4. The method according to any of claims 1 to 3,
wherein in the mixing step, the resultant grinding chips are mixed with coke and a
solidification assistant (D) for obtaining powder (E) containing the coke and solidification
assistant (D).
5. The method according to any of claims 1 to 4,
wherein the crushed brittle compact (C) is further admixed with recovery dusts collected
in a steelmaking process.
6. The method according to claim 5,
wherein the recovery dusts are admixed in an amount of 10 to 30 wt%.
7. The method according to any of claims 1 to 6,
wherein the solidification assistant (D) is at least one selected from the group consisting
of rice polishings, blackstrap molasses, starches, calcined lime, colloidal silica,
silicate of soda, aluminum phosphate, vinyl acetate sludge, asphalt emulsion and bentonite.
8. The method according to any of claims 1 to 7,
wherein the solidification assistant (D) is admixed in an amount of 1 to 10 wt%.
9. The method according to any of claims 4 to 8,
wherein the coke is admixed in an amount of 5 to 50 wt%.
10. The method according to any of claims 1 to 9,
wherein the employed cotton-like aggregates (B) are adjusted for the content of water
to less than 50 wt% and for the content of oil to less than 10 wt%.
11. The method according to any of claims 1 to 10,
wherein the brittle compact (C) is adjusted for the content of water of
2 to 12 wt% and for the content of oil to 1 to 5 wt%.
12. The method according to any of claims 1 to 11,
wherein immediately after the compression molding step the briquette (A) is subjected
to quick cooling.
13. The method according to any of claims 1 to 12,
wherein a product substantially shaped like a pillow is obtained as the briquette
(A).
14. The method according to any of claims 1 to 13,
wherein a material containing not less than 0.2 wt% of carbon is employed as the grinding
chips.